Cabin Smell

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themissingelf
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Cabin Smell

Post by themissingelf »

Hi. Ever since I've owned my Mk3 (c. 1 year) I'm troubled by the smell in the cabin...

The smell...
It's a combination of "old car" and/or exhaust and/or oil and /or "engine" but not obviously any single one of them. Slightly acrid. It's most noticeable when I first open the car and then, once the roof is down and /or windows open it fades with only the occasional stronger whiff returning as I drive. I quite often become aware of it when I turn right. At first I thought it may be the leather interior (that being probably the only material in the cabin likely to be giving off any type of odour) but it's not really a leathery smell.

So far
  • I've been all over the exhaust looking for leaks. Nothing. Despite having a slightly loud after market exhaust there's no obvious sound of leaking exhaust either.
  • Replaced the hood drainage flaps - just in case they were allowing fumes to be sucked in.
  • Spent time sniffing the engine bay with the car running - nothing obvious.
  • Bought a diagnostic tester and discovered P0141 and P0135 sensor heater element faults - yet to investigate source of problem.
  • Removed the storage cubby holes to check firewall grommets etc - as far as I can tell they're all in good shape. Also to be sure my UK car has NOT got one of the notorious USA carbon something-or-other fuel vent / filter things (it hasn't).
  • Removed the under bonnet plastic cover - not really sure what I'm looking for, just getting a little desperate
  • Peered at the engine bay, hoses etc; wondering whether it might have something to do with crankcase ventilation?
I'm completely foxed and therefore grateful for any advice / suggestions.

Do MR2 Roadsters simply smell?!



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Re: Cabin Smell

Post by MRHAPPY62 »

I would think stagnent water in the storage behind the seats !
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Re: Cabin Smell

Post by jimi »

Perhaps it's a result of the problem that's giving you the DTC error codes
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Re: Cabin Smell

Post by Topdownman »

The carpet is waterproofed on the bottom side so any water that has got under there will lead to rust/smells etc and will never go away of its own accord! There is a very absorbant thick wadding under the carpet that holds a lot of water!

You can check by taking the kick plate trims off and gwetting your hand under the carpet to see if there is any dampness apparent. If you do find any, get the seats, centre console, bin doors off and pull the carpet forward to see how wet it is and dry it out.

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Topic author
themissingelf
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Re: Cabin Smell

Post by themissingelf »

Many thanks for the replies. Definitely no water in or under the storage bins - they're all currently removed and I can see bare metal. I will, however, check the footwells. It's not obviously a damp, wet smell but then it not obviously any particular type of smell :)

I did wonder about the codes - they relate to the pre and post CAT oxygen sensors but describe a heating element fault which I'd imagine is only significant when the engine is cold. Once up to heat I'd assumed the sensor heaters were redundant? Maybe not - I'm not an expert. I'm going to test the circuits and see where the fault lies and fix in any case.

The other thing that caught my attention if the access panel to the fuel tank... I didn't realise what it was until I checked the maintenance manual so I'll be getting my nose near to see if there's anything drifting in via that area.

Thanks again.
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Re: Cabin Smell

Post by ayresyboy »

take the carpet out completely and give it a good wash. failing that, peg on your nose 😆 andy
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themissingelf
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Re: Cabin Smell

Post by themissingelf »

Car is bone dry in the bin area and footwells. No sign of ever having water ingress.
Checked around the fuel tank access panel - no obvious smell.
The only other thing I can think of is the soft top - in particular the area leading down to the drains etc... Maybe needing a good clean.
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Re: Cabin Smell

Post by MR2DI4 »

Failed O2 sensor and the car is running default rich.

Not sure about your fuel over there but the Mobil 8000 over here is very smelly on a cold start, you cannot miss it.

Also if things are not right with the engine fuel mixture the catalytic converters don't like it and can result in a smell as well.

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themissingelf
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Re: Cabin Smell

Post by themissingelf »

Thank you. I did wonder about the sensors. The fault code talks about a "heater" so I (perhaps wrongly) assumed that the smell would go once the car was up to heat (and the heater component of the sensor) was redundant. All hypothesis - I'm no expert.

The car has always had strong exhaust fumes on start up so can quite believe it's the root cause.

I'm hoping to trace the fault with the sensors this weekend and fix.

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themissingelf
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Re: Cabin Smell

Post by themissingelf »

In case it's of interest...

Replaced all three sensors today (only two were faulty - one of the two manifold sensors, and the one post cat).

Been out on a couple of drives and so far so good. The occasional whiff of exhaust - nowhere near as strong, momentary instead of persistent, and occasional instead of frequent, and obviously exhaust vs. kinda exhaust. What I'd expect for an open top sports car.

The car drove well before I replaced the sensors and only the heaters were producing an error. However... The car is now driving so much better - pulls strong from low down in the rev range - eager in a way it wasn't before.

The jury remains out - I've had the smell go away in the past after some fettering so I'm cautiously optimistic!
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Re: Cabin Smell

Post by MR2DI4 »

Pre cat manifold sensors are more important than the post cat ones in terms of engine control.

It's not all about the heater in them that just helps them to start working faster on a cold start they age and their respose time slows or they get poisoned with crud or just plain fail.
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